Zubay G, Lederman M
Proc Natl Acad Sci U S A. 1969 Feb;62(2):550-7. doi: 10.1073/pnas.62.2.550.
The operon model was proposed by Jacob and Monod in 1961 to explain the regulation of enzyme synthesis in bacteria. The model requires two genetic elements: a locus i which directs the synthesis of a repressor, and a locus called the operon which contains an operator gene and associated structural genes. The repressor is believed to stop RNA and enzyme synthesis by combining with the operator site. The inhibiting effect of the repressor is reversed by an inducer which interacts directly with the repressor. A DNA-dependent cell-free system has been developed for studying the regulation of the operon containing the gene for beta-galactosidase enzyme. In this cell-free system, gene activity is indirectly measured by the synthesis of part of the enzyme. Qualitatively, the regulation of the operon in the cell-free system is similar to its regulation in intact cells. The cell-free system is used to advantage in experiments where it is desirable to use predetermined levels of repressor, operon, and inducer. Such quantitative studies suggest that two inducer molecules are most effective in removing the repressor from the gene.
操纵子模型是雅各布和莫诺德在1961年提出的，用于解释细菌中酶合成的调控机制。该模型需要两个遗传元件：一个是指导阻遏物合成的基因座i，另一个是称为操纵子的基因座，它包含一个操纵基因和相关的结构基因。据信，阻遏物通过与操纵位点结合来阻止RNA和酶的合成。阻遏物的抑制作用可被诱导物逆转，诱导物直接与阻遏物相互作用。已经开发出一种依赖DNA的无细胞系统，用于研究含有β-半乳糖苷酶基因的操纵子的调控。在这个无细胞系统中，基因活性通过部分酶的合成来间接测量。定性地说，无细胞系统中操纵子的调控与其在完整细胞中的调控相似。无细胞系统在需要使用预定水平的阻遏物、操纵子和诱导物的实验中具有优势。此类定量研究表明，两个诱导物分子在将阻遏物从基因上移除方面最为有效。
